Volume 14 Issue 10, October 2018

The agent responsible for the accelerated expansion of the Universe is completely unknown. Delicate interference measurements of the quantum transitions of very slow neutrons bouncing on a flat table have constrained an interesting theoretical possibility.

Large-scale quantum computations are hampered by the propagation of errors. Experiments have now demonstrated the deterministic teleportation of a quantum gate, which prevents error propagation by using a combination of quantum and classical bits.

Mapping cell lineages onto a problem in graph theory suggests that physical principles regulate cell positioning during egg development in the fruit fly — providing an elegant example of how physics can advance our understanding of biology.

Are there limits to the applicability of textbook quantum theory? Experiments haven’t found any yet, but a new theoretical analysis shows that treating your colleagues as quantum systems might be a step too far.

It is the common wisdom that time evolution of a many-body system leads to thermalization and washes away quantum correlations. But one class of system — referred to as many-body localized — defy this expectation.

Recent developments have seen concepts originally developed in quantum information theory, such as entanglement and quantum error correction, come to play a fundamental role in understanding quantum gravity.

Quantitative tools for measuring the propagation of information through quantum many-body systems, originally developed to study quantum chaos, have recently found many new applications from black holes to disordered spin systems.

The state of a superconducting circuit qubit governs the photonic heat flow through an integrated assembly, constituting a quantum heat valve that provides a testbed for exploring quantum thermodynamics in a circuit quantum electrodynamics setting.

Demonstration of a passive swap gate between the states of a fibre-guided photonic qubit and a single atom.

The authors theoretically investigate a novel form of a Doppler effect in homogeneous systems with positive refractive index that occurs under certain conditions. It is suggested that this Doppler effect can be experimentally separated from other Doppler effects by using polaritons such as those found in graphene.

The demonstration of substantially enhanced high-harmonic emission from a silicon metasurface suggests a route towards novel photonic devices based on a combination of ultrafast strong-field physics and nanofabrication technology.

A neutron scattering study of the three-dimensional antiferromagnet Cu₃TeO₆ uncovers evidence for topological crossings in the magnon spectra of this system.

The organization of small clusters of connected cells confined to an egg chamber during early development can be mapped onto a tree packing problem. Entropically preferred packing configurations are shown to arise more readily in experiment.

A spectroscopic approach based on the Rabi resonance method is used to probe the quantum states of ultracold neutrons—and thus their interaction with the gravitational potential of the Earth.

The physical conditions that support a geometric interpretation of spacetime, such as the equivalence between rest and inertial mass, are shown not to be necessarily valid in the quantum regime, and a quantum formulation is provided.

Certification of high-dimensional entanglement is required for improved quantum communication protocols, and is now shown to be achievable in an efficient manner by measuring quantum states twice in two different bases.

A mechanical-mediated quantum-compatible microwave–optical converter achieves high efficiency through a feed-forward protocol that harnesses correlations in the output noise.

The Kerr and Faraday effects enable routing of light in an applied magnetic field. Now a new class of magneto-optical phenomena is proposed and demonstrated in which light emission is controlled perpendicular to the external magnetic field.

A generalized Mott-insulating state is found theoretically starting from a holographic model. The state has features in common with the conventional variety, and upon doping shares striking similarities with the stripe phases found in cuprates.

A phase transition between metallic and insulating states is observed to simultaneously happen in two ways at once. The bulk of the sample shows an instantaneous jump in the conductivity, while 1D domain walls show a slow switching into a metallic state.

The authors study intermolecular Coulomb decay that occurs in a sample of THF and water in a reaction microscope employing triple-coincidence measurements of two ions and one electron. They find that ICD is a previously unconsidered effect between water and other organic molecules that are hydrogen-bonded, with ICD outpacing proton transfer.

October 23 is (unofficially) known by some chemists as Mole Day. Andrea Taroni attempts to get to grips with the concept of the mole itself, and the imminent change to its definition.